It is clear in my mind that the FIA and Formula 1 have a serious problem of effective and equitable adjudication and defining proper racing.
To give Vettle a 20 sec penalty for that pass is absolutely insane, given the way the FIA has ruled in the past. Just looking beyond the fact that had Vettle stayed on the track, Button would have collided with him as they were side-by-side and thus ended the race for both of them (is that the result the FIA would have preferred?) There is plenty of history of passing while off track has been allowed and gone unpunished.
Some have argued that this case is different because the actual pass took place off track (one car's nose moving past the other car's nose) but I'd say that where the actual 'pass' takes place is irrelevant to the entire discussion, and the only thing that matters is does the car gain any advantage by going full off track, and what was avoided by going full off track.
I will argue that going 4 wheels off track ALWAYS provides an advantage if you can continue racing as it means you went into the turn or whatever faster than you should have and thus gained some time. If we want to fix this issue, ensure that the full width of the car is just wider than ANY shoulder and thus if 4 wheels go off the farthest off wheels are then in gravel or a wall. Simple and effective.
However, I have seen many cases where cars pass off the track and no action is taken. Think back several years to any number of starts where cars pile into the first turn and many cars drive outside the track and around, rather than slotting in behind other cars to stay 'on track' and end up passing cars that did stay 'on track', or avoided the congestion of staying on track.
If staying on track is to be THE expectation, then the FIA must enforce it in ALL cases, not just when it happens to be to be a pass in the points positions at the end of the race. ALL times, be it in turn one amoung the pack, or a driver all by themselves. I hope next time the drivers just crash into each other and we'll have that to deal with, but at least they stayed on track. Right FIA?